Support Android's per-app language setting #27
Description
The language selector in the app is kind of a legacy UI - now that Android supports per-app language settings (System Settings → System → Languages → App languages), we should support that and eventually get rid of the in-app language selector.
https://support.google.com/android/answer/12395118
https://developer.android.com/guide/topics/resources/app-languages
https://android-developers.googleblog.com/2022/11/per-app-language-preferences-part-1.html
Related to #25